1. Field of the Invention
The present invention relates to a fuel injection controlling apparatus for an internal combustion engine, and particularly to a technology for controlling a fuel injection timing in starting an internal combustion engine.
2. Description of the Related Art
In an internal combustion engine such as a gasoline engine or the like, a fuel injection controlling apparatus for determining a fuel injection timing or a fuel injection amount (fuel injection period) in response to an operational condition of the engine. A so-called intake non-synchronous injection system for injecting fuel in synchronism with an intake stroke of each cylinder in starting the internal combustion engine is known as such a fuel injection controlling apparatus. The intake non-synchronous injection type fuel injection controlling apparatus is an apparatus for performing the fuel injection before an intake valve is opened.
By the way, since it is difficult to gasify the fuel such as gasoline or the like at an extremely low temperature and it is likely that the fuel would adhere to a wall surface or the like, in the case where the intake non-synchronous injection type fuel injection controlling apparatus starts the internal combustion engine at an extremely low temperature, it is necessary to inject a large amount of fuel exceeding an amount of fuel to be adhered to an intake port or the like in advance.
Then, the fuel that has been adhered to the wall surface of the intake port or the like is subjected to an intake vacuum pressure that is increased in accordance with the increase of an RPM of the engine after the completion of the start and is sucked into a combustion chamber. Accordingly, there is a fear that the mixture within the combustion chamber becomes an enriched atmosphere to cause the emission to be worse.
In order to solve such a problem, a fuel injection apparatus for an internal combustion engine is disclosed in Japanese Patent Application Laid-open No. Sho 62-210230. This fuel injection apparatus is provided with a start timing detecting means for detecting a start timing of the engine, a temperature detecting means for detecting a temperature of the engine, and a means for performing the synchronous fuel injection in an intake stroke on the basis of the outputs of the above-described start timing detecting means and the above-described temperature detecting means if the temperature of the engine in starting is less than a predetermined value and is an intake synchronous injection type fuel injection apparatus for injecting fuel in synchronism with a valve opening timing of an intake valve of each cylinder.
In the intake synchronous injection type fuel injection apparatus, since the fuel injection is performed in synchronism with the valve opening timing of the intake valve in starting the internal combustion engine, it is possible to feed a major portion of the fuel injected from the fuel injection valve directly into the combustion chamber. As a result, the amount of fuel adhered to the intake port or the like is decreased, and at the same time, the fuel increment value in starting becomes small in comparison with the intake non-synchronous injection type.